In the processing of light-sensitive color photographic materials for photographing as typified by light-sensitive photographic materials in which the silver halide comprises silver iodobromide, it has been hitherto common to use in a final processing step subsequent to a washing bath a stabilizing solution containing formaldehyde.
The formaldehyde used in the above stabilizing solution is effective for preventing changes in physical properties of light-sensitive color photographic materials, in particular, changes in gradation that may occur when scratches are produced on the surfaces of light-sensitive color photographic materials or light-sensitive photographic materials are gradually hardened with time. The formaldehyde is also known to be effective against the deterioration of dye images that may be caused by an unreacted coupler remaining in light-sensitive color photographic materials.
However, the formaldehyde added in the stabilizing solution for the purpose of, e.g., stabilizing dye images may form an adduct together with sulfite ions that adhere to a light-sensitive material and are brought into it from a forebath (a processing solution having a fixing ability), not only resulting in a decrease in the originally intended dye image stabilizing effect, but also causing a promotion of sulfiding disadvantageously.
To solve these problems, it has been proposed to use an alkanol amine as disclosed in U.S. Pat. No. 4,786,583. Use of the alkanol amine, however, tends to have an ill influence to the prevention of yellow staining at a non-image portion, and also can not be said to bring about a satisfactory effect for the prevention of sulfiding.
Meanwhile, in U.S.A., CIIT (Chemical Industry Institute of Toxicology) has reported that formaldehyde caused nasal foramen cancer in rats as a result of administration of 15 ppm of formaldehyde. NIOSH (National Institute for Occupational Safety and Health) and ACGIH (American Conference of Governmental Industrial Hygienists) also state that there is a possibility of producing a cancer. In Europe also, use of formaldehyde is strongly regulated. In West Germany, formaldehyde has been so regulated since 10 years ago as to be in a concentration of 0.1 ppm or less in residential areas.
In Japan also, in token of the harmfulness of formaldehyde, there have been legislations concerning poisons and powerful drags because of its stimulative action to the mucous membrane, regulations to organic solvent toxication, according to the Specified Chemical Substances Troubles Preventive Rule of the Occupational Safety and Health Law, regulations on household utensils, regulations relating to fibers and veneer boards, and also formaldehyde regulations put into operation as from 1975 with regard to undershirts and baby's clothing. Thus, people have longed for a technique by which the formaldehyde can be decreased.
As techniques of making substantially zero, or decreasing, the content of formaldehyde in stabilizing solutions, Japanese Patent Publications Open to Public Inspection [hereinafter referred to as Japanese Patent O.P.I. Publication(s)] No. 27742/1987 and No. 151538/1986 disclose use of hexahydrotriazine compounds and U.S. Pat. No. 4,859,574 discloses use of N-methylol compounds, as means for achieving the above objects.
The hexahydrotriazine compounds can prevent dyes from being discolored in an environment of high temperature and high humidity even if formaldehyde has been made substantially zero, but have the problem that they are not effective in an environment of low humidity, e.g., a relative humidity of 20% or less. They have also have a problem in the storage stability of stabilizing solutions although not so serious as formaldehyde, in particular, the problem that the sulfiding tends to occur. It has been made clear that the storage stability is particularly questioned when a stabilizing solution is used in processing over a long period of time, when used in processing in a small quantity, or when used in a low replenishing rate.
As for the N-methylol compounds, when used as substitute compounds of formaldehyde, they have the problems that the effect of preventing discoloration of dyes and the storage stability of stabilizing solutions can not be satisfactory and that an attempt to prevent discoloration of dyes results in a great deterioration of the storage stability of stabilizing solutions.
There is also a disclosure of a method in which hexamethylenetetramine compounds are used in stabilizing solutions, which, however, like the hexahydrotriazine compounds, are disadvantageous in that they are not well effective for preventing discoloration of dyes in an environment of low humidity.
In recent years, there is an increase in photofinishing laboratories that handle processing in a small quantity, and the storage stability of stabilizing solutions has come into question. In particular, because of the low-replenishment processing that has come to the front for the purpose of lowering environmental pollution, it is difficult for any conventional techniques to cope with this problem.